Magnetic X-ray spectroscopy of two-dimensional CrI3 layers

The recently confirmed monolayer ferromagnet CrI3 is a frisky example of a two-dimensional ferromagnetic material with great application potential in van der Waals heterostructures. Here we present a soft X-ray absorption spectroscopy study of the magnetic bulk properties of CrI3, giving insight into the magnetic coupling scenario which is relevant for understanding its thickness-dependent magnetic properties. The experimental Cr L2,3 X-ray magnetic circular dichroism spectra show a good agreement with calculated spectra for a hybridized ground state. In this high-spin Cr ground state the Cr-I bonds show a strongly covalent character. This is responsible for the strong superexchange interaction and increased spin-orbit coupling, resulting in the large magnetic anisotropy of the two-dimensionally layered CrI3 crystal.